This is an archived article and the information in the article may be outdated. Please look at the time stamp on the story to see when it was last updated.

Please enable Javascript to watch this video

PHOENIX -- Two people are dead and a Department of Public Safety trooper who was wounded while responding to a shots fired call along Interstate 10 near Tonopah just might owe his life to an armed passerby who stopped at exactly the right time.

KPHO reports it started shortly before 4:30 a.m. Thursday with a 911 call from a driver east of California who said somebody shot at his car from the median. According to Col. Frank Milstead, the directors of DPS, that's the call to which the trooper was responding when he came upon a single-vehicle rollover wreck near Tonopah. A woman had been ejected from that vehicle.

DPS Capt. Damon Cecil said the trooper, a 27-year-veteran of the agency, was ambushed by the suspect when he got out of his vehicle at the scene of the rollover. That's when the trooper was shot and wounded.

"A physical fight between our trooper and that suspect then ensued, at which time the suspect was shot and killed," Cecil said. "Right now that's all we have. This is a fluid investigation."

Milstead, speaking from the hospital to which his trooper and taken, said an "uninvolved third party" who was driving by saw the trooper grappling with the suspect and stopped to help, eventually shooting and killing the suspect.

That civilian, using the wounded trooper's radio, was the one who alerted DPS to the shooting.

"To the civilian on the DPS trooper's radio, if you can hear me, I need you to let me know where the suspect is that got in an altercation with our trooper," the dispatcher could be heard saying on the scanner.

"The suspect is uh, occasionally breathing or stirring. He's been shot by a passerby," the man with the wounded trooper's radio calmly responded. "He's laying right next to the officer."

While it's early in the investigation, Cecil said initial indications are that the man who shot the trooper might have been involved in the initial rollover. It's not clear how or even if the suspect and the woman from the rollover were connected. Neither one has been identified.

"At this time, we don't know exactly how the events played out other than our trooper got on scene at that rollover collision after responding to a shots fired call and then he was subsequently ambushed and shot," Cecil said. "Investigators are interviewing witnesses, interviewing our trooper. They're the ones who are going to be able to solidify the timeline for us."

The wounded trooper, who was shot in the right shoulder, was air-lifted from the scene to Abrazo West Campus in Goodyear. Video from there showed him being wheeled on a gurney from the medical helicopter into the hospital. His injury reportedly is serious but not life-threatening.

Milstead tweeted shortly before 7:30 a.m., about three hours after the shooting, that the trooper likely "will be okay [sic] after some recovery."

A couple of hours later, he said his trooper was in stable condition and would be undergoing surgery.

At this point, DPS is not releasing the trooper's name, saying only that he has worked the same stretch of I-10 for more than two decades.

Javier Soto reported from the hospital that Fallon, the Golden Retriever that joined the Arizona Counter Terrorism Intelligence Center (ACTIC) almost a year ago, had been brought in to provide emotional support.

Like, the trooper, the woman from the rolled vehicle was air-lifted to the hospital where she later died.

Traffic ground to a halt

While most westbound drivers stopped by the closure of I-10 were able to turn around in the median, several semis were stuck for longer.

Kenny Dunn, the driver of one of those rigs, said he was heading west on I-10 early Thursday when a single trooper passed him, the lights on his patrol vehicle flashing.

Dunn came upon the aftermath of the shooting several miles down the road.

"There was still smoke kinda over from the rolled over vehicle," Dunn explained.

He went on to say he saw one of the medical helicopters land a few minutes later. That was the chopper that picked up the wounded trooper.

"He was here maybe 10 minutes at the most," Dunn said.

A second chopper then picked up the woman ejected from the rolled vehicle.

The closure on I-10 is expected to in place until this afternoon.

ADOT said drivers should consider alternate routes, including State Route 85 and Interstate 8. Eastbound lanes of I-10 remain open.

Tonopah is a little less than an hour's drive west of Phoenix.

This is the second shooting involving a law enforcement officer in the Valley so far this year. There were 46 such incidents in the Valley in 2016, plus another 36 in other parts of the state for a total of 82.